The present invention relates generally to rotating electric machinery and, more particularly, to a method and system for communicating voltage regulator switching information to a vehicle computer.
Generators are found in virtually every motor vehicle manufactured today. These generators, also referred to as alternators, produce electricity necessary to power a vehicle's electrical accessories, as well as to charge a vehicle's battery. Generators must also provide the capability to produce electricity in sufficient quantities so to power a vehicle's electrical system in a manner that is compatible with the vehicle's electrical components. The alternator or generator typically uses a voltage regulator to regulate the charging voltage and output current in order to provide consistent operation during varying loads that would otherwise create voltage drops and other operational problems. Presently, conventional vehicle charging systems may utilize a voltage regulator having either a discrete transistor or, alternatively, a custom integrated circuit known as an Application Specific Integrated Circuit (ASIC).
Still other vehicle designs may also employ voltage regulators with advanced microprocessor functions that maintain a highly accurate regulated voltage produced by a generator. Microprocessor based regulators may also include advanced clock and memory circuits that store battery and power supply reference data, battery voltage and generator rotation speed, as well determine how much the battery is being charged and at what rate at any point in time.
Notwithstanding the particular type of regulator design (e.g., discrete components, ASIC, microprocessor), the regulator typically provides a pulse width modulation (PWM) signal to be applied to a switching device that selectively passes current through a field coil of the alternator. By varying the duty cycle of the PWM signal, the amount of current can be increased or decreased, thereby increasing or decreasing the output voltage of the alternator. In modern vehicles, an electronic control module (ECM) serves as the main vehicle computer, and thus is in communication with the voltage regulator. However, it may be the case that the ECM is incompatible with the PWM signal that is applied to the driver of the power switching device. That is, an actual PWM signal may include several transient depending on the addition/subtraction of electrical loads to the system, instead of a smooth, average PWM signal. In such a case, conventional systems may require the use of additional (and expensive) components to filter the true PWM signal for communication to the ECM.
Accordingly, it would be desirable to be able to communicate PWM switching information to a vehicle computer in a manner that overcomes the above mentioned disadvantages.